Plastic suds container for a washing machine

ABSTRACT

A plastic suds container for a washing machine for receiving a drum rotatable therein includes a container wall including a cylindrical shell and an end wall at an end of the shell. The end wall defines a plane and includes a stabilizing device and a number of channel-like relief profiles formed therein in limited regions within respective areas bounded by the stabilizing device. Each of the relief profiles includes a hollow, the hollow being at least substantially surrounded by a remaining flat or unprofiled region of the respective area bounding the stabilizing device. Each of the relief profiles is expandable and/or compressible in a respective direction of extension of the plane.

Priority is claimed to German patent application DE 10 2005 019 414.1, filed Apr. 25, 2005, the entire subject matter of which is hereby incorporated by reference herein.

The present invention relates to a plastic suds container for a washing machine for receiving a drum rotatable therein, the plastic suds container having cylindrical shell and at least one end wall closing the shell, the shell and/or the end wall being provided with stabilizing means.

BACKGROUND

In the prior art, plastic suds container for washing machines have been described which take the form of a cylindrical container enclosing the drum. In one of the end walls, a metallic cross-shaped bearing member including a hub for receiving a drive shaft for the drum is incorporated in the molded plastic mass. Injection-molding around the cross-shaped bearing member made of cast iron leads to considerable internal stresses, which result from the fact that the plastic shrinks as it cools from its solidification temperature to ambient temperature. The resulting forces acting on the cross-shaped bearing member are so high that the cross-shaped bearing member may deform. In addition, the forces can lead to cracks in the container wall, resulting in leaks and unstable connection of the cross-shaped bearing member.

When injection-molding around large-volume metal parts, generally, considerable internal stresses occur in the plastic, which also lead to stresses in the metal part. This may possibly even lead to deformations of the metal part, and thus make the composite construction useless. Of course, it is possible, for example, to heat the metal part such that the metal part and the plastic shrink to the same extent during cooling, and that the two parts remain stress-free. However, this has the disadvantage that significant energy costs are incurred, and that the handling in the manufacture of a cross-shaped bearing member incorporated in a plastic suds container is thereby made much more difficult. Another problem is the unequal heating of the cross-shaped bearing member and the suds container during operation. Here too, material stresses may occur within the container wall due to the different temperature expansion coefficients, leading to the problems mentioned earlier.

British publication GB 2 333 300 A describes a plastic suds container having a bearing hub embedded in injection-molded plastic. Here, reinforcing ribs formed on and extending from the hub transfer and distribute the forces from the hub to the end wall of the suds container over as large an area as possible. In that approach, however, after the cooling process during the manufacture of the plastic suds container is completed, material stresses may be present in the transition regions between the hub and the plastic part. Moreover, the material accumulations in the area of the ribs may shrink to different extents during cooling, and may therefore lead to unwanted force peaks and/or material stresses in the transition regions. Excessive material stresses may lead to unwanted cracks, resulting in leakage of the suds container.

European Patent EP 0 835 729 B1 describes a plastic suds container for a washing machine. Said suds container has circular surface depressions formed in one end wall. These surface depressions are provided with ribs in the manner of a grid. The circular surface depressions have a higher thermal conductivity than the remaining portion of the end wall or container wall.

SUMMARY OF THE INVENTION

It is, therefore, an object of the present invention to provide a plastic suds container for a washing machine, in which is incorporated a cross-shaped bearing member or bearing hub made of metal, and which has improved durability and reduced susceptibility to cracking.

The present invention provides a plastic suds container for a washing machine for receiving a drum rotatable therein. The plastic suds container includes a container wall having a cylindrical shell and an end wall at an end of the shell, the end wall defining a plane. The end wall includes a stabilizing device and a plurality of channel-like relief profiles formed therein in limited regions within respective areas bounded by the stabilizing device. Each of the relief profiles includes a hollow, the hollow being at least substantially surrounded by a remaining flat or unprofiled region of the respective area bounding the stabilizing device. Each of the relief profiles is expandable and/or compressible in a respective direction of extension of the plane.

The present invention also provides a plastic suds container for a washing machine for receiving a drum rotatable therein. The plastic suds container includes a container wall having a cylindrical shell and an end wall at an end of the shell, the end wall defining a plane. The end wall includes a molded plastic portion, a metallic cross-shaped bearing member being disposed in the molded plastic portion. The bearing member includes a hub configured to receive a drive shaft for the drum and includes at least one brace extending substantially radially outwardly from the hub. The end wall includes a plurality of channel-like relief profiles formed therein in limited regions within respective areas bounded by the stabilizing device. Each of the relief profiles includes a hollow, the hollow being at least substantially surrounded by a remaining flat or unprofiled region of the respective area bounding the stabilizing device. Each of the relief profiles is expandable and/or compressible in a respective direction of extension of the plane.

The present invention also provides a plastic suds container for a washing machine for receiving a drum rotatable therein. The plastic suds container includes a container wall having a cylindrical shell and an end wall at an end of the shell, the end wall defining a plane. The end wall includes a stabilizing device and defines a plurality of channel-like relief profiles adjacent to respective flat or unprofiled areas in respective regions bounded by the stabilizing device. Each of the relief profiles is expandable and/or compressible in a respective direction of extension of the plane.

Advantages that can be achieved with the present invention are that the internal stresses within the plastic suds container, mainly in the plane of its container wall, are reduced by molding-in channel-like indentations (also referred to as relief profiles), so that the durability and/or load-carrying capacity of the plastic suds container, i.e., of the container wall, are increased.

The molded-in indentations are limited to certain regions, whereby partial elasticity is provided only in locations where the highest forces or force peaks occur. These force peaks frequently occur in container wall areas that are surrounded or enclosed by stabilizing means. Possible stabilizing means include, for example, ribs or a cross-shaped bearing member inserted in the plastic material. The molded-in indentations are designed such that the container wall forms a hollow as seen in the cross-sectional profile, said hollow being elastic in the direction of extension of the container wall because of its shape. The remaining areas of the container wall, which are not deformed by indentations molded therein, surround the molded-in indentation or relief profile completely or at least substantially completely, thereby providing that the stability is maintained to the extent possible. Thus, forces resulting from stresses in the direction of extension of the plane of the container wall are taken up and/or compensated for by these molded-in indentations, which are deformable with respect to expansion and/or compression. Forces that are introduced by the shrinking plastic material into the metal part embedded therein can be reduced as well. In this manner, on the one hand, the metal part is relieved from stress itself and, on the other hand, the stresses developing in the plastic material are also reduced by the resilient effect of the elastic molded-in indentations.

The geometry of the profile is decisive for the function, because the resilient effect is greatest in the direction transverse to the indentation. In the longitudinal direction, i.e., under bending load, the profile can act as a stiffening rib. The ideal geometry can be found if the internal stresses in the component are known. However, since this is rarely the case, the profiles are designed such that they are preferably well suited for a plurality of directions in which forces act. Therefore, in accordance with the present invention, the relief profiles provided in the area of the container wall are meander-shaped, star-shaped, oval, circular, or spherical in shape, the spherical relief profile corresponding only to the impression of a sphere that has been pressed in partially. In particular, the spherical relief profile takes up internal stresses in nearly all directions in the plane of the container wall, and is therefore well suited for nearly all directions of expansion or shrinkage.

In a suitable embodiment, the thickness of the container wall in the area of the relief profiles is selected to be equal to the thickness of the remaining unprofiled areas. Because the relief profiles partially change the orientation of the container wall, the forces resulting from internal material stresses are also deflected in a defined manner according to the pattern of the relief profiles. This prevents stresses and/or force peaks from occurring in the material of the container wall.

In an alternative embodiment of the plastic suds container, the thickness of the container wall in the area of the relief profiles is selected to be smaller than the thickness of the remaining unprofiled areas. In this manner, any possible deformation caused by the forces resulting from the internal material stresses is mainly limited to the area of the relief profiles. In this area, the deformability is increased due to the reduced wall thickness.

In one suitable embodiment, the wall thickness in the area of the relief profiles is selected to be one-half to two-thirds of the thickness of the remaining unprofiled areas of the container wall.

In case of a reduced wall thickness, it is advantageous to provide a stepless or smooth transition between the greater original wall thickness and the reduced wall thickness. The transition is in the area of the respective relief profiles, but may also extend into the adjacent unprofiled area. A continuous transition between normal and reduced wall thickness avoids forces peaks in this transition region, thereby increasing the durability of the suds container.

The above-mentioned relief profiles can be used to advantage in plastic suds containers having components, such as a hub or counterweights, which are embedded in injection-molded plastic, and which are made of other materials and may cause internal stresses in the container wall because of their different cooling characteristic with respect to time. Another reason for internal stresses in the container wall lies in different thicknesses of the plastic, such as reinforcing ribs or integrally connected components. This is primarily the case at locations which have different wall thicknesses and cannot be modified for functional reasons or for reasons of stability, such as rigid connection points. In this case, it is also advantageous to use the relief profiles described above.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the present invention will be explained with reference to the following FIGS. 1 through 6.

FIG. 1 shows a plastic suds container in a perspective view.

FIG. 2 shows another embodiment of a plastic suds container according to the present invention.

FIG. 3 depicts meander-shaped relief profiles.

FIG. 4 shows star-shaped relief profiles.

FIG. 5 illustrates oval relief profiles.

FIG. 6 shows spherical relief profiles.

DETAILED DESCRIPTION

FIG. 1 is a perspective view of a plastic suds container 1 for a washing machine. A drum (not shown in detail) is rotatably mounted in plastic suds container 1. This is a view looking into the interior of a cut-open plastic suds container 1. Plastic suds container 1 substantially includes a cylindrical shell 2 and at least one end wall 3. In one end wall 3, a metallic cross-shaped bearing member 4 including a hub 5 for receiving a drive shaft for the drum is incorporated in the plastic mass. This is shown especially in FIG. 2.

As can be seen, in particular, from the perspective views of FIGS. 1 and 2, end wall 3 is provided with relief profiles 6, which are intended to absorb the internal stresses occurring when the plastic shrinks as it cools from its solidification temperature to ambient temperature. End wall 3 has stabilizing means in the form of ribs integrally formed thereon and a cross-shaped bearing member 4 embedded in the plastic mass, said cross-shaped bearing member having a central hub 5 and braces 14 extending radially outwardly from hub 5. Relief profiles 6 are each located in areas 8 bounded by stabilizing means 14, 16 and are completely surrounded by the remaining flat wall within these areas 8. Relief profile 6 has a bulge directed toward the interior of the container and has a curved pattern of limited length in plane 13 of end wall 3. A bulge toward the outside of the container is also conceivable. Arrows 13 indicate, by way of example, just four directions of extension in the plane of end wall 3. However, these four directions are not intended to have a limiting effect with respect to other directions of extension of relief profiles 6.

The function of a relief profile 6 is illustrated in FIG. 5. The cross-sectional view clearly shows the hollow-shaped relief profile 6. In this example, stresses occurring within container wall 3 lead to forces in direction 13 a and further internal forces in opposite direction 13 b. The hollow-shaped bulge of relief profile 6 allows for partial displacement of container wall 3 in the direction of acting forces 13 a and 13 b, whereby the center or apex 9 of relief profile 6 is moved in direction 15, and the depth of the hollow is reduced. The resulting forced movement or expansion in the direction of extension of plane 13 in the presence of forces 13 a and 13 b permits internal stresses to be reduced or completely removed.

FIG. 2 is an elevation view of the end wall showing cross-shaped bearing member 4 embedded in the plastic. Stresses resulting from the different temperature expansion coefficients of metallic cross-shaped bearing member 4 and of the plastic may occur in areas 8, which are bounded by arms 14 of cross-shaped bearing member 4. The patterns of the relief profiles 6 are selected such that they cover as extensive an area as possible for any occurring material stresses or force peaks, and that they are capable of absorbing such force peaks by partial deformation within relief profiles 6.

The corresponding shapes of relief profiles 6, which are formed in the injection mold, are shown in greater detail in FIGS. 3, 4, 5 and 6. Also, relief profiles 6 may preferably be provided on the end wall 3 of container 2, in which is incorporated metallic cross-shaped bearing member 4. Relief profiles 6 can be meander-shaped, as shown in FIG. 3. In another variant shown in FIG. 4, relief profile 6 is star-shaped, while FIG. 5 illustrates a suitable variant of a relief profile 6 whose pattern is oval in plane.

FIG. 6 shows a spherical relief profile 6 incorporated in-plane. As will be apparent from the cross-sectional view of FIG. 6, the wall thickness in the area of apex 9 within relief profile 6 is smaller than the wall thickness in the remaining unprofiled area 10. In transition region 11, the wall thickness decreases steadily, whereby in the event of a partial deformation within relief profile 6, stress peaks are avoided in this transition region 11. Due to the shape of relief profile 6 and/or the reduction in wall thickness, increased elasticity is provided in this region compared to the remaining area 12 of the container wall.

The present invention has been described with reference to exemplary embodiments, which are not intended to limit the scope of the invention. 

1. A plastic suds container for a washing machine for receiving a drum rotatable therein, the plastic suds container comprising a container wall including a cylindrical shell and an end wall at an end of the shell, the end wall defining a plane, the end wall including a stabilizing device, the end wall including a plurality of channel-like relief profiles formed therein in limited regions within respective areas bounded by the stabilizing device, each of the relief profiles including a hollow, the hollow being at least substantially surrounded by a remaining flat or unprofiled region of the respective area bounding the stabilizing device, each of the relief profiles being at least one of expandable and compressible in a respective direction of extension of the plane.
 2. The plastic suds container as recited in claim 1 wherein the relief profiles include at least one of a meander-shape, a star-shape, an oval shape, a circular shape, and a spherical shape in the plane.
 3. The plastic suds container as recited in claim 1 wherein a thickness of the end wall in an area of at least one of the relief profiles is equal to a thickness of an unprofiled area of the wall.
 4. The plastic suds container as recited in claim 1 wherein a thickness of the end wall in an area of at least one of the relief profiles is smaller than a thickness of an unprofiled area of the wall.
 5. The plastic suds container as recited in claim 4 wherein the thickness of the end wall in the area of the at least one of the relief profiles is one-half to two-thirds of the thickness of the unprofiled area of the wall.
 6. The plastic suds container as recited in claim 4 wherein the at least one of the relief profiles includes a transition region wherein the thickness of the end wall continuously decreases from the thickness of the unprofiled area to the thickness in the area of the at least one of the relief profiles.
 7. The plastic suds container as recited in claim 4 wherein the at least one of the relief profiles includes a groove.
 8. A plastic suds container for a washing machine for receiving a drum rotatable therein, the plastic suds container comprising a container wall including a cylindrical shell and an end wall at an end of the shell, the end wall defining a plane, the end wall including a molded plastic portion, a metallic cross-shaped bearing member being disposed in the molded plastic portion, the bearing member including a hub configured to receive a drive shaft for the drum and including at least one brace extending substantially radially outwardly from the hub, the end wall including a plurality of channel-like relief profiles formed therein in limited regions within respective areas bounded by the stabilizing device, each of the relief profiles including a hollow, the hollow being at least substantially surrounded by a remaining flat or unprofiled region of the respective area bounding the stabilizing device, each of the relief profiles being at least one of expandable and compressible in a respective direction of extension of the plane.
 9. The plastic suds container as recited in claim 8 wherein the relief profiles include at least one of a meander-shape, a star-shape, an oval shape, a circular shape, and a spherical shape in the plane.
 10. The plastic suds container as recited in claim 8 wherein a thickness of the end wall in an area of at least one of the relief profiles is equal to a thickness of an unprofiled area of the wall.
 11. The plastic suds container as recited in claim 8 wherein a thickness of the end wall in an area of at least one of the relief profiles is smaller than a thickness of an unprofiled area of the wall.
 12. The plastic suds container as recited in claim 11 wherein the thickness of the end wall in the area of the at least one of the relief profiles is one-half to two-thirds of the thickness of the unprofiled area of the wall.
 13. The plastic suds container as recited in claim 11 wherein the at least one of the relief profiles includes a transition region wherein the thickness of the end wall continuously decreases from the thickness of the unprofiled area to the thickness in the area of the at least one of the relief profiles.
 14. The plastic suds container as recited in claim 11 wherein the at least one of the relief profiles includes a groove.
 15. A plastic suds container for a washing machine for receiving a drum rotatable therein, the plastic suds container comprising a container wall including a cylindrical shell and an end wall at an end of the shell, the end wall defining a plane, the end wall including a stabilizing device, the end wall defining a plurality of channel-like relief profiles adjacent to respective flat or unprofiled areas in respective regions bounded by the stabilizing device, each of the relief profiles being at least one of expandable and compressible in a respective direction of extension of the plane. 